Physiological And Molecular Mechanisms Of Phoxim Degradation In Tomato Regulated By Trichoderma Asperellum

The residue of oganophosphorus pesticide is crucial to human health and the sustainable development of vegetable industry in China.There’s already study showed that Trichoderma asperellum were able to promote the degradation and transformation of organic pollutants,but the mechanism remains elusive.Taking the large amount application of phoxim as model oganophosphorus pesticide,we will investigate the effects of T.asperellum on the residues and residual dynamics of phoxim in tomato roots in this study.On this basis,we will explore the absorption,transportation and degradation mechanism of phoxims in tomato after inoculation of T.asperellum.Furthermore,the study is constructed interacted with Trichoderma and phoxim.The biochemical pathways of phoxim metabolism induced by Trichoderma and key gene expression in regulatory pathways is analyzed.The main results of the study were as follow:1.The inoculation of Trichoderma TM significantly reduced the residual amount of phoxim in the root of tomato,and improved the degradation efficiency of phoxim.The residual amount of phoxim decreased rapidly after 5d,and it was reduced to 4.25mg Kg~-11 FW in 15d.2.The POD and PPO activity of tomato roots were significantly enhanced after the inoculation of Trichoderma TM.And inoculating Trichoderma TM before the treatment of phoxim promoted the enhancement more obviously.The POD and PPO activity increased by 1.24 times and 0.81 times compared to the treatment of phoxim.The inoculation of Trichoderma TM increased the content of As A and GSH in tomato roots,reduced the content of DHA significantly,and increased AsA/DHA significantly.In comparison with the treatment of only phoxim,inoculating Trichoderma TM before the treatment of phoxim increased the content of As A,AsA/DHA and GSH by 64.47%,122.88%and 61.64%.Compared with control group,the inoculation of Trichoderma TM increased the activity of GST by 2.64 times,and the addition of phoxim increased the activity of GST by 30.41%.Inoculating Trichoderma TM before the treatment of phoxim increased the activity of GST by 2.89 times compared with the treatment of phoxim.3.With the inoculation of Trichoderma TM,the expression of detoxification genes of tomato roots CYP724B2,GST1,GST2,GST3,GSH,GR,ABC2 and GPX were significantly improved by 2.35,2.55,3.14,3.19,11.78,5.51,1.17 and 4.01 times compared to control group.Compared with phoxim treatment only,the expression of detoxification genes of tomato roots CYP724B2,GST1,GST2,GST3,GSH,GR,ABC2and GPX increased by 2.82,2.49,3.41,2.21,3.60,2.08,6.89 and 1.46 times.4.According to the transcriptome sequencing and sequence alignment of different treatment,the total number of reads on the comparison was 135,076,504,the average efficiency ratio reached 70.71%.488 new genes were found,of which 367 were functional annotations.Differentially expressed genes were analyzed.A total of 6genes are related to signal transduction and secondary metabolism,and 2 differentially expressed genes are related to plant signal transduction.And the 8 differential genes were tested by qRT-PCR.